This invention is generally directed to utilization of high bandwidth channels available on existing cable television systems to serve personal computer users. This invention is more specifically directed to providing split channel signaling between personal computer users and service (information) providers to which the computer users subscribe. Communications from the users to the providers is transmitted via a relatively low-speed communication channel, such as over the public switched telephone network. At least one high-speed data transmission path is available in a cable television system which also serves the user to carry data originated by the service providers to the user.
Enhanced service providers may provide a gateway to a plurality of databases containing information which is provided to subscribers which typically use personal computers connected by a modem to the gateway. Although conventional modem technology has continued to advance and thus, provide increased data rates through the public switched telephone network, transmission speeds of less than 30 kilobits per second represents a relatively slow data rate in a multimedia environment in which high resolution color pictures, sounds and animation require substantially faster transmission speeds in order to provide acceptable performance as viewed by the personal computer user.
Relatively wide bandwidths, such as 6 megahertz channels, afforded by cable television systems provide an attractive media for transmitting information to computer users at substantially greater rates than can be accomplished by modem transmission over the public switched telephone network. However, existing cable television systems are primarily designed for one-way communications from the cable distribution head-end of the cable television network to each of the cable television subscribers distributed along the cable network. In those cable television systems which provide upstream signaling, the upstream channel is often inadequate to support a plurality of users contending for use of the upstream channel. Thus, the use of a cable television system alone cannot support the communication need of a personal computer user with regard to the need for upstream communications from the user to the service providers.
In U.S. Pat. No. 4,862,268, a control system for addressable cable television is disclosed which permits the transmission of data using a video format. Data is transmitted in a video format during the vertical blanking interval of a normal television signal.
An interactive videotex system is described in U.S. Pat. No. 5,093,718 wherein a plurality of nodes is distributed along a cable TV system. Each node serves a small group of users and contains in its memory substantially all information needed to communicate with its group of users. A central computer or processing center provides data to the nodes and provides updates for information stored at the nodes. Thus, the small group of users supported by each node can be provided relatively high-speed data transfer rates of information from the associated node.
Broadband RF signals have been combined with baseband signals on a single distribution cable; see in U.S. Pat. No. 5,255,267. RF signals above 35 megahertz are simultaneously present with baseband signal below 25 megahertz on a single cable. From a single personal computer node coupled to the cable, baseband signals are propagated in both directions while permitting the RF signals to propagate only in a single direction from the RF head-end equipment towards the end of the cable.
A hybrid access system has been proposed to provide remote computer users with high-speed (up to 10 megabits per second) access to the Internet network for high-speed downstream data transfer to the users while simultaneously permitting independent lower speed upstream channels to be utilized to transmit user requests for information. It is understood that such a product has been marketed by Hybrid Networks, Inc.
Cable modems operating at speeds up to 10 megabits per second over cable television cables are available from Zenith Electronics and General Instrument Corporation. Thus, there exists a capability for encoding conventional digital information onto a radio frequency (RF) channel of a cable television system and decoding the RF information back into baseband digital data.
A need exists for an apparatus and method which maximizes use of existing facilities such as a cable television distribution network to provide enhanced downstream data transfer to users with personal computers while simultaneously permitting users to provide effective uplink communications to service providers which originate the information sought by the users.